On Wednesday, August 15, 2012 08:36:35 PM Thiago Macieira wrote: > On quarta-feira, 15 de agosto de 2012 22.05.02, Konstantin Tokarev wrote: > > From wiki: > > > > "QPA on Qt4.8 only makes sense on OpenGL Hardware! If you don?t have > > OpenGL > > HW there is absolutely no point in choosing Qt4.8-QPA over Qt4.8-QWS" > > The wiki is wrong. > > There's a lot of reason for choosing QPA, regardless of OpenGL support or > lack thereof. There are also reasons for choosing QWS instead of QPA, even > with OpenGL hardware, if those reasons are stronger than the best > adaptation to OpenGL (example: the QWS display server).
Seconded, that wiki line is BS. Using QPA with the linuxfb plugin on 4.8 for single-process applications is way more efficient than QWS, both memory- and FPS-wise. QWS enables composition and server-side rendering by default, which has a huge impact for the performance of the transfer-to-framebuffer phase. QPA with linuxfb doesn't have any of that. You can disable it when configuring Qt, but there's no documented option, you have to pass -D flags manually. If you're doing it, then yes you get similar display performance between QWS and QPA. But by default QPA wins. The only thing QWS buys you is built-in (and ugly) window decorations, as well as multi-process support. For everything else it's just a legacy framework with lots of overhead and a constant source of performance problems imho. > > In Qt 5, QPA is more complete and works on the desktop systems. > > > Does Qt5-QPA on non-OpenGL hardware perform not worse than Qt4.8-QWS? > > Of course. Performance has nothing to do with it, since in your case > everything will be running software rendering anyway.
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